When the edges of an African violet or other houseplant’s leaves turn brown, it’s usually a sign of stress caused by cultural conditions within the home. Correcting these conditions can keep further browning at bay.
Brown leaf edges are the plant form of frostbite; being exposed to lower-than-normal temperatures affects the edges of the plant first. Browning edges are usually a sign that the plant has been "shocked" by a short duration of cold temperatures, such as during a short power outage, or being moved to a location where cold drafts are common. Sixty degrees Fahrenheit is the lowest temperature African Violets should be exposed to.
If you’ve been away from home for several days and your African Violet has gone without water, brown leaf edges may be the result. African Violets like moist but well-drained soil, and a period of dryness can cause leaf browning.
Over-application of fertilizer can also cause browning of leaf edges. Fertilize your African Violet with a solution labeled for use on African Violets, and apply only as directed and as often as directed to prevent further damage to your plant.